I have an 01 1800A, after starting and warning up, when at idle the engine surges, using a volt meter to check voltage coming to battery terminal the number will fluctuate from 10 point something volts to 14 point something volts, and if I turn the high beams on and/ or the driving/fog lights the surge comes at a faster pace and slows back down when I turn the high beams and fog lights back off, could this be a result of a bad alternator? any and all answers will be appreciated, thanks in advance.

Try doing an idle learn procedure. Let it completely cool off, with the side stand down start the engine without touching the throttle and let it idle until the fans come on and go off, do not touch the throttle or you have to start over.

just went and tried the idle learn procedure, no luck, I tried this back last summer but didn't know to do it with the side stand down so I tried it again with the same result, the surge starts long before the cooling fans ever kick on, the lights dim down and come back to normal when the idle is surging that's why I thought it may be the alternator but i'm not by any means a mechanic, again any suggestions are more than welcome.

How low does the battery voltage decrease when you turn on the ignition without starting the engine?

For the voltage to take such a large dip as 10 volts while running indicates that something is is sucking a LOT of juice, or as you are thinking, the alternator ceases to put out a charging voltage.

I know that when I start my 2003 the voltage stays low, abut 11.0 volts, for a few seconds and then comes up. I do not know what causes this and I never really worried about it because it is normal operation on the two 2003 GL1800's that I have owned.

I suspect that the ECM has something to do with this. Perhaps Dave0430 can shed some more light on this issue.

How low does the battery voltage decrease when you turn on the ignition without starting the engine?

For the voltage to take such a large dip as 10 volts while running indicates that something is is sucking a LOT of juice, or as you are thinking, the alternator ceases to put out a charging voltage.

I know that when I start my 2003 the voltage stays low, abut 11.0 volts, for a few seconds and then comes up. I do not know what causes this and I never really worried about it because it is normal operation on the two 2003 GL1800's that I have owned.

I suspect that the ECM has something to do with this. Perhaps Dave0430 can shed some more light on this issue.

The ECM controls the ignition/cruise relay which in turn causes the alternator to begin charging after about 8 seconds, why 8 seconds I don't know. Then it has to be running @ 800+ RPM to charge. I suspect the surge is causing it to drop below 800 where it shuts off the alternator then it kicks back in when the RPM goes up.
Try pulling the #19 fuse then start the engine. This will disable the alternator and should tell if it's the alternator causing the surge or the surge affecting the alternator. Adjusting the idle speed (which ain't easy) may fix this. Or just cleaning the throttle body may be in order.

Dave0430, I will try this in the next day or two and post results, thanks again for your advice, I had the throttle body cleaned by my local Honda dealer late 2016 just after this problem started with no resolution to the problem, they were puzzled by it also.

Dave0430, I will try this in the next day or two and post results, thanks again for your advice, I had the throttle body cleaned by my local Honda dealer late 2016 just after this problem started with no resolution to the problem, they were puzzled by it also.

Yeah, dealerships tend to say that a lot. "First time we have ever seen that problem". I dunno if they just have poor memory. I was told by my dealerships mechanic, when they had one, and a riding partner of mine was experiencing this that it could be the MAF. My buddy died before ever tracing it down, and his bike was sold out of town so we never learned if it might have been the problem with the surging. Just throwing this out as something you could check. I have seen a mod for the MAF somewhere here that puts a resistor inline with the MAF circuitry that supposedly smooths out surging.

Dave0430, I did what you suggested about pulling the #19 fuse and starting the bike, I let it run at idle for somewhere between 15-20 minutes and the surge WAS NOT PRESENT, so I shut it off and replaced the fuse and started it back, the SURGE RETURNED within just a few seconds so I shut it off and removed the fuse again, started it back up and let it run a little over 5 minutes with NO SURGE at all, so is this definitely a BAD alternator? Thanks again

Dave0430, I did what you suggested about pulling the #19 fuse and starting the bike, I let it run at idle for somewhere between 15-20 minutes and the surge WAS NOT PRESENT, so I shut it off and replaced the fuse and started it back, the SURGE RETURNED within just a few seconds so I shut it off and removed the fuse again, started it back up and let it run a little over 5 minutes with NO SURGE at all, so is this definitely a BAD alternator? Thanks again

Your battery and charging system needs checked to know for sure. It all starts with making sure the battery connections are clean and tight, and then testing the battery. If your Wing has a verified healthy battery, then test the charging system. Anything short of doing all that is speculation.

GoldWingrGreg, as I posted before the battery is new,but I read your comment and took it out and load tested it because I know sometimes you can get defective “new” batteries, it tested fine so I did the test that Dave0430 suggested again with the same results, no surge with the #19 fuse removed but when I reinstalled the fuse the surge returned within a few seconds of restarting the bike, do you also think this surge at idle could be a bad alternator or is there something else in the charging system that I should check, by the way I have a new alternator on it’s way, thanks again

Another though I have is the IAC valve may be sticking and when the alternator kicks in it lets the idle drop too low so the ECM cuts out the alternator, then the IAC overcompensates and makes the idle go high, the alternator kicks in again, then brings it back down and again lets it go too low, repeat.
Mia01wing , with the #19 fuse pulled and the engine warmed up rev the engine then let the throttle go, does it ease back down to idle or does it drop below the normal idle speed then pick back up?

ok guys and gals, I'm back, after installing a new alternator and starting the bike I have some changes in the voltage of the battery, it stays at 14.30 at idle BUT the surge at idle is still there, not as bad, but still there, the voltage DOES NOT change with the idle surge like before so I'm sure the alternator WAS bad, so now my ? is could it fall back to the voltage regulator being the problem as I rode the bike with this surge for over 2 years and had a new battery go bad during this same time period? also I did the test with the bike warmed up that included pulling the #19 fuse and starting the bike and revving the engine and letting go of the throttle and it went smoothly back down to idle without falling below normal idle RPM. any and all replies are much appreciated, thanks again.

GoldWingrGreg, as I posted before the battery is new,but I read your comment and took it out and load tested it because I know sometimes you can get defective “new” batteries, it tested fine so I did the test that Dave0430 suggested again with the same results, no surge with the #19 fuse removed but when I reinstalled the fuse the surge returned within a few seconds of restarting the bike, do you also think this surge at idle could be a bad alternator or is there something else in the charging system that I should check, by the way I have a new alternator on it’s way, thanks again

From post above. "You need to test the battery and the charging system." What were the results the charging system test ??? From the Service Manual "With the headlight on high beam, restart the engine. Measure the voltage on the multimeter when the engine runs at 2,000 rpm." The measurement is taken across the battery terminals.

GoldWingerGreg, I did the charging system test as you described above, the bike running, high beam headlights on, and the engine RPM's at 2000, the volt meter reading at the battery terminals was 14.35

GoldWingerGreg, I did the charging system test as you described above, the bike running, high beam headlights on, and the engine RPM's at 2000, the volt meter reading at the battery terminals was 14.35

That's a normal reading. The spec. is between battery voltage and not higher the 15.5v. Battery voltage is what the battery voltage is with the bike off.

so, I have a new alternator, a new battery, I have cleaned all connections between the two and I still have the surge, does anyone have any other ideas on what could be causing this surge, last winter I had the bike torn apart to where I had access to the throttle body because a local "expert" told me I had a air/vacuum leak somewhere, with the bike running I used starting fluid, per his advice, and sprayed it at the base of the throttle body, while the air filter housing was still assembled, along all the vacuum hoses, anywhere and everywhere he told me to try, he said if there was a leak that this would cause the engine to rev up, and of course nothing, I put new spark plugs in it at that time also, is there any more things any of you can think of that might be causing this surge, I'm open to any and all suggestions, Dave0430 even maybe adjusting the idle if you could walk me through that, again thanks in advance. signed, lost and confused!!!

I have an 01 1800A, after starting and warning up, when at idle the engine surges, using a volt meter to check voltage coming to battery terminal the number will fluctuate from 10 point something volts to 14 point something volts, and if I turn the high beams on and/ or the driving/fog lights the surge comes at a faster pace and slows back down when I turn the high beams and fog lights back off, could this be a result of a bad alternator? any and all answers will be appreciated, thanks in advance.

Using the tach, approximately how much is the RPM change ??? Does it die ??? Does this happen during warm up (0mins-20mins) or at operating temperature (after the fans cycle) ??? Will it do this when coming to a stop, or while sitting in a garage ??? Any surge at 2,000rpms.

Although you have a new battery, and you've tested it with a load tester, I'm interested in your batteries health ... I'm interested in your battery being tested how the Service Manual wants it tested. Also, what is the amp hour rating on your battery ... 17amp/hr, 17.5, 18, 20 ???

Also, GL1800's come with only a cable attached to each post. If your posts have more then just a cable attached to each, remove the others ... does any thing change ??? Are your cables clean and tight ???

Please, please, please, to save time, please answer all the above. That way we don't have to keep back tracking.